U.S. patent number 11,027,465 [Application Number 16/141,127] was granted by the patent office on 2021-06-08 for methods for forming rotor blades having foam cores.
This patent grant is currently assigned to TEXTRON INNOVATIONS INC.. The grantee listed for this patent is Bell Helicopter Textron Inc.. Invention is credited to James A. Cordell, Andrew Paul Haldeman, Dalton T. Hampton, Suvankar Mishra, Jesse J. Wrabel.
United States Patent |
11,027,465 |
Cordell , et al. |
June 8, 2021 |
Methods for forming rotor blades having foam cores
Abstract
A method is provided in one example embodiment and may include
positioning at least one nozzle within a hollow portion of a rotor
blade at a distance associated with a span of the rotor blade and
providing, via the at least one nozzle, a liquid foam mixture in
the hollow portion, wherein the liquid foam expands and becomes a
solid foam material that fills the hollow portion of the rotor
blade. Another method is provided in another example embodiment and
may include providing a plurality of openings for a rotor blade
that are positioned proximate to a hollow portion of the rotor
blade and providing a liquid foam mixture in the hollow portion of
the rotor blade through at least one opening of the rotor blade,
wherein the liquid foam mixture expands and becomes a solid foam
material that fills the hollow portion of the rotor blade.
Inventors: |
Cordell; James A. (Azle,
TX), Mishra; Suvankar (Carrollton, TX), Haldeman; Andrew
Paul (Fort Worth, TX), Wrabel; Jesse J. (Fort Worth,
TX), Hampton; Dalton T. (Fort Worth, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Bell Helicopter Textron Inc. |
Fort Worth |
TX |
US |
|
|
Assignee: |
TEXTRON INNOVATIONS INC. (Fort
Worth, TX)
|
Family
ID: |
1000005602142 |
Appl.
No.: |
16/141,127 |
Filed: |
September 25, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200094450 A1 |
Mar 26, 2020 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C
44/18 (20130101); B29C 44/422 (20130101); B29C
44/3415 (20130101); B64C 11/26 (20130101); B29C
44/60 (20130101); B29L 2031/082 (20130101); B29L
2031/087 (20130101); B64C 2027/4736 (20130101); F05D
2300/612 (20130101) |
Current International
Class: |
B29C
44/18 (20060101); B64C 11/26 (20060101); B29C
44/34 (20060101); B29C 44/60 (20060101); B29C
44/42 (20060101); B64C 27/473 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
J6 Polymers LLC, JFOAM.TM. BX-450 Product Bulletin, date unknown, 2
pages. cited by applicant.
|
Primary Examiner: Yi; Stella K
Attorney, Agent or Firm: Patent Capital Group
Claims
What is claimed is:
1. A method comprising: positioning at least one nozzle within a
hollow portion of a rotor blade at a distance associated with a
span of the rotor blade, wherein the hollow portion of the rotor
blade has a fixed volume between an outboard end and an inboard end
of the rotor blade; and providing, via the at least one nozzle, a
liquid foam mixture in the hollow portion, wherein the liquid foam
expands and becomes a solid foam material that fills the hollow
portion of the rotor blade; wherein the hollow portion of the rotor
blade is defined, at least in part, by an aft wall of a spar of the
rotor blade, at least a portion of an inner surface of an upper
skin of the rotor blade, at least a portion of an inner surface of
a lower skin of the rotor blade, and a forward wall of a trailing
edge wedge of the rotor blade for the span of the rotor blade.
2. The method of claim 1, wherein the distance is based, at least
in part, on a center of the fixed volume of the hollow portion of
the rotor blade.
3. The method of claim 1, wherein providing the liquid foam mixture
in the hollow portion further comprises at least one of: moving the
rotor blade away from the at least one nozzle at one or more rates
as the liquid foam mixture is provided in the hollow portion of the
rotor blade; removing the at least one nozzle from the hollow
portion at one or more rates as the liquid foam mixture is provided
in the hollow portion of the rotor blade; adjusting a flow rate
that the liquid foam mixture is provided in the hollow portion of
the rotor blade; tilting the rotor blade along an inboard-outboard
axis as the liquid foam mixture is provided in the hollow portion
of the rotor blade; and tilting the rotor blade along a forward-aft
axis during as the liquid foam mixture is provided in the hollow
portion of the rotor blade.
4. The method of claim 3, wherein tilting the rotor blade along the
inboard-outboard axis includes tilting the outboard end of the
rotor blade downward between 15 degrees and 75 degrees.
5. The method of claim 3, wherein tilting the rotor blade along the
forward-aft axis includes tilting a leading edge of the rotor blade
downward between 15 degrees and 75 degrees.
6. The method of claim 3, further comprising one of: heating the
liquid foam mixture; and cooling the liquid foam mixture.
7. The method of claim 6, wherein heating the liquid foam mixture
includes heating the liquid foam mixture to a temperature greater
than 100 degrees Fahrenheit.
8. The method of claim 6, wherein cooling the liquid foam mixture
includes cooling the liquid foam mixture to a temperature less than
70 degrees Fahrenheit.
9. The method of claim 1, wherein the distance is one of a
plurality of distances associated with the span of the rotor blade,
and providing the liquid foam mixture further comprises: providing
the liquid foam mixture in the hollow portion between the outboard
end and the inboard end of the rotor blade at each distance of the
plurality of distances, wherein the position of the at least one
nozzle at each distance is maintained for a period of time and
wherein the period of time at each distance is the same or
different.
10. The method of claim 1, further comprising: providing at least
one opening for the hollow portion of the rotor blade to allow
outgassing as the liquid foam mixture expands and becomes the solid
foam material.
11. The method of claim 1, wherein the solid foam material adheres
to an upper skin of the rotor blade, a lower skin of the rotor
blade, a spar of the rotor blade, and a trailing edge wedge of the
rotor blade.
12. A method comprising: providing a plurality of openings for a
rotor blade, wherein the plurality of openings are positioned
proximate to a hollow portion of the rotor blade, and the hollow
portion of the rotor blade has a fixed volume between an outboard
end and an inboard end of the rotor blade; and providing a liquid
foam mixture in the hollow portion of the rotor blade through at
least one opening of the plurality of openings of the rotor blade,
wherein the liquid foam mixture expands and becomes a solid foam
material that fills the hollow portion of the rotor blade; wherein
the at least one opening of the plurality of openings has an
inboard-outboard diameter and a forward-aft diameter, and the
inboard-outboard diameter and the forward-aft diameter are
different.
13. The method of claim 12, wherein providing the liquid foam
mixture in the hollow portion of the rotor blade further comprises:
pouring the liquid foam mixture into the hollow portion using at
least one opening of the plurality of openings.
14. The method of claim 12, wherein the liquid foam mixture is
provided into the hollow portion of the rotor blade at a particular
opening located at a distance that is based, at least in part, on a
center of the fixed volume of the hollow portion rotor blade
between the outboard end and the inboard end of the rotor
blade.
15. The method of claim 12, wherein the fixed volume of the rotor
blade comprises a plurality of sub-volumes and the liquid foam
mixture is provided into the hollow portion of the rotor blade at a
plurality of openings, wherein each opening is located at a
distance that is based, at least in part, on a center of each
sub-volume.
16. The method of claim 12, wherein providing the liquid foam
mixture in the hollow portion further comprises at least one of:
tilting the rotor blade along an inboard-outboard axis as the
liquid foam mixture is provided in the hollow portion of the rotor
blade; and tilting the rotor blade along a forward-aft axis during
as the liquid foam mixture is provided in the hollow portion of the
rotor blade.
17. The method of claim 12, wherein providing the liquid foam
mixture in the hollow portion further comprises: injecting the
liquid foam mixture through at least one opening of the plurality
of openings using a foam delivery system, wherein the liquid foam
mixture is injected through the at least one opening at one or more
flow rates.
18. The method of claim 17, wherein the at least one opening is
located at one of: an inboard end of the rotor blade; an upper skin
of the rotor blade; a lower skin of the rotor blade; and a trailing
edge of the rotor blade.
19. The method of claim 17, further comprising at least one of:
tilting the rotor blade along an inboard-outboard axis as the
liquid foam mixture is injected; and tilting the rotor blade along
a forward-aft axis during as the liquid foam mixture is
injected.
20. The method of claim 19, further comprising one of: heating the
liquid foam mixture prior to the injecting; and cooling the liquid
foam mixture prior to the injecting.
21. The method of claim 12, wherein providing at least one opening
of the plurality of openings allows outgassing as the liquid foam
mixture expands and becomes the solid foam material.
22. The method of claim 12, wherein: at least one opening is
provided through a skin of the rotor blade; and at least one
opening is provided through a trailing edge of the rotor blade.
23. The method of claim 12, further comprising: sealing the
plurality of openings of the rotor blade after the liquid foam
mixture expands and becomes the solid foam material.
24. The method of claim 23, wherein the plurality of openings are
sealed using a composite material.
25. The method of claim 12, wherein the hollow portion of the rotor
blade is defined, at least in part, by an aft wall of a spar of the
rotor blade, at least a portion of an inner surface of an upper
skin of the rotor blade, at least a portion of an inner surface of
a lower skin of the rotor blade, and a forward wall of a trailing
edge wedge of the rotor blade for a span of the rotor blade.
26. The method of claim 12, wherein the solid foam material adheres
to an upper skin of the rotor blade, a lower skin of the rotor
blade, a spar of the rotor blade, and a trailing edge wedge of the
rotor blade.
Description
TECHNICAL FIELD
This disclosure relates in general to the field of aircraft and,
more particularly, though not exclusively, to methods for forming
rotor blades having pourable/injected foam cores.
BACKGROUND
There are numerous considerations involved in the design and
manufacture of components for aircraft, such as tiltrotor aircraft
and rotorcraft, including size, weight, power efficiency, fuel
efficiency, noise, vibration, structural loads, and so forth. For
example, manufacturing processes for rotor blades is often
extremely challenging and can implicate numerous considerations
which may impact the ability to manufacture rotor blades in a cost
and/or time efficient manner.
SUMMARY
According to one aspect of the present disclosure, a method may be
provided and may include positioning at least one nozzle within a
hollow portion of a rotor blade at a distance associated with a
span of the rotor blade, wherein the hollow portion of the rotor
blade has a fixed volume between an outboard end and an inboard end
of the rotor blade; and providing, via the at least one nozzle, a
liquid foam mixture in the hollow portion, wherein the liquid foam
expands and becomes a solid foam material that fills the hollow
portion of the rotor blade. The hollow portion of the rotor blade
may be defined defined, at least in part, by an aft wall of a spar
of the rotor blade, at least a portion of an inner surface of an
upper skin of the rotor blade, at least a portion of an inner
surface of a lower skin of the rotor blade, and a forward wall of a
trailing edge wedge of the rotor blade for the span of the rotor
blade. In at least one instance, the distance at which the nozzle
is positioned within the hollow portion of the rotor blade may be
based, at least in part, on a center of the fixed volume of the
hollow portion of the rotor blade. The solid foam material may
adhere to an upper skin of the rotor blade, a lower skin of the
rotor blade, a spar of the rotor blade, and a trailing edge wedge
of the rotor blade.
In various instances providing the liquid foam mixture in the
hollow portion may include at least one of: moving the rotor blade
away from the at least one nozzle at one or more at one or more
rates as the liquid foam mixture is provided in the hollow portion
of the rotor blade; removing the at least one nozzle from the
hollow portion at one or more rates as the liquid foam mixture is
provided in the hollow portion of the rotor blade; adjusting a flow
rate that the liquid foam mixture is provided in the hollow portion
of the rotor blade; tilting the rotor blade along an
inboard-outboard axis as the liquid foam mixture is provided in the
hollow portion of the rotor blade; and tilting the rotor blade
along a forward-aft axis during as the liquid foam mixture is
provided in the hollow portion of the rotor blade. In some
instances, the method may include providing at least one opening
for the hollow portion of the rotor blade to allow outgassing as
the liquid foam mixture expands and becomes the solid foam
material.
In some instances, tilting the rotor blade along the
inboard-outboard axis may include tilting the outboard end of the
rotor blade downward between 15 degrees and 75 degrees. In still
some instances, tilting the rotor blade along the forward-aft axis
may include tilting a leading edge of the rotor blade downward
between 15 degrees and 75 degrees. In still some instances,
providing the liquid foam mixture in the hollow portion may include
one of heating the liquid foam mixture; and cooling the liquid foam
mixture. Heating the liquid foam mixture may include heating the
liquid foam mixture to a temperature greater than 100 degrees
Fahrenheit. Cooling the liquid foam mixture may include cooling the
liquid foam mixture to a temperature less than 70 degrees
Fahrenheit.
In some instances the distance may be one of a plurality of
distances associated with the span of the rotor blade, and
providing the liquid foam mixture may further include providing the
liquid foam mixture in the hollow portion between the outboard end
and the inboard end of the rotor blade at each distance of the
plurality of distances, wherein the position of the at least one
nozzle at each distance is maintained for a period of time and
wherein the period of time at each distance is the same or
different.
According to another aspect of the present disclosure, another
method may be provided and may include providing a plurality of
openings for a rotor blade, wherein the plurality of openings are
positioned proximate to a hollow portion of the rotor blade, and
the hollow portion of the rotor blade has a fixed volume between an
outboard end and an inboard end of the rotor blade; and providing a
liquid foam mixture in the hollow portion of the rotor blade
through at least one opening of the plurality of openings of the
rotor blade, wherein the liquid foam mixture expands and becomes a
solid foam material that fills the hollow portion of the rotor
blade.
In some instances, providing the liquid foam mixture in the hollow
portion of the rotor blade may include pouring the liquid foam
mixture into the hollow portion using at least one opening of the
plurality of openings. In some instances, the at least one opening
of the plurality of openings may have an inboard-outboard diameter
and a forward-aft diameter in which the inboard-outboard diameter
and the forward-aft diameter are different.
In some instances, the liquid foam mixture may be provided into the
hollow portion of the rotor blade at a particular opening located
at a distance that is based, at least in part, on a center of the
fixed volume of the hollow portion rotor blade between the outboard
end and the inboard end of the rotor blade. In some instances, the
fixed volume of the rotor blade may include a plurality of
sub-volumes and the liquid foam mixture may be provided into the
hollow portion of the rotor blade at a plurality of openings,
wherein each opening is located at a distance that is based, at
least in part, on a center of each sub-volume.
In various instances, providing the liquid foam mixture in the
hollow portion of the rotor blade may include at least one of:
tilting the rotor blade along an inboard-outboard axis as the
liquid foam mixture is provided in the hollow portion of the rotor
blade; and tilting the rotor blade along a forward-aft axis during
as the liquid foam mixture is provided in the hollow portion of the
rotor blade.
In still some instances, providing the liquid foam mixture in the
hollow portion of the rotor blade may include injecting the liquid
foam mixture through at least one opening of the plurality of
openings using a foam delivery system, wherein the liquid foam
mixture is injected through the at least one opening at one or more
flow rates. The at least one opening may be located at one of: an
inboard end of the rotor blade; an upper skin of the rotor blade; a
lower skin of the rotor blade; and a trailing edge of the rotor
blade. In various instances, the injecting may further include at
least one of tilting the rotor blade along an inboard-outboard axis
as the liquid foam mixture is injected; and tilting the rotor blade
along a forward-aft axis during as the liquid foam mixture is
injected. In still some instances, the injecting may further
include one of heating the liquid foam mixture prior to the
injecting; and cooling the liquid foam mixture prior to the
injecting. At least one opening of the plurality of openings may
allow outgassing as the liquid foam mixture expands and becomes the
solid foam material. In some instances at least one opening may be
provided through a skin of the rotor blade and/or at least one
opening may be provided through a trailing edge of the rotor
blade.
The method may further include sealing the plurality of openings of
the rotor blade after the liquid foam mixture expands and becomes
the solid foam material. In some instances, the plurality of
openings may be sealed using a composite material.
In at least one instance the hollow portion of the rotor blade may
be defined, at least in part, by an aft wall of a spar of the rotor
blade, at least a portion of an inner surface of an upper skin of
the rotor blade, at least a portion of an inner surface of a lower
skin of the rotor blade, and a forward wall of a trailing edge
wedge of the rotor blade for a span of the rotor blade. The solid
foam material may adhere to an upper skin of the rotor blade, a
lower skin of the rotor blade, a spar of the rotor blade, and a
trailing edge wedge of the rotor blade.
According to another aspect of the present disclosure a rotor blade
may be provided and may include an upper skin and a lower skin; at
least one spar between the upper skin and the lower skin; a core
area between the upper skin and the lower skin and between the at
least one spare and a trailing edge of the rotor blade; and a foam
material in the core area, wherein the foam material is provided in
the core area after the upper skin and the lower skin are bonded to
the at least one spar. The foam material may be provided in the
core area as a liquid foam mixture that converts to a solid foam
material that fills the core area and adheres to components that
that define the core area. In some instances, the rotor blade may
further include a trailing edge wedge, wherein the upper skin and
lower skin are bonded to the at least one spar and the trailing
edge wedge, and the foam material is provided in the core area
after the upper skin and the lower skin are bonded to the at least
one spar and the trailing edge wedge.
BRIEF DESCRIPTION OF THE DRAWINGS
To provide a more complete understanding of the present disclosure
and features and advantages thereof, reference is made to the
following description, taken in conjunction with the accompanying
figures, in which like reference numerals represent like
elements.
FIGS. 1A-1B and 2 are simplified schematic diagrams of example
aircraft, in accordance with certain embodiments.
FIGS. 3A-3E are simplified diagrams illustrating example details
that may be associated with a rotor blade, in accordance with
certain embodiments.
FIGS. 4-6 are simplified diagrams illustrating example details that
may be associated with a foam system that may be used to fill a
core area of a rotor blade, in accordance with certain
embodiments.
FIGS. 7A-7C are simplified diagrams illustrating example details
that may be associated with forming an example rotor blade, in
accordance with certain embodiments.
FIGS. 8A-8D are simplified diagrams illustrating example details
that may be associated with providing a liquid foam mixture in a
core area of a rotor blade, in accordance with certain
embodiments.
FIGS. 9A-9C are simplified diagrams illustrating example details
that may be associated with providing a liquid foam mixture in a
core area of a rotor blade using a foam delivery system, in
accordance with certain embodiments.
FIGS. 10A-10B are simplified diagrams illustrating example details
that may be associated with another example rotor blade, in
accordance with certain embodiments.
FIGS. 11A-11C are simplified diagrams illustrating other example
details that may be associated with providing a liquid foam mixture
in a core area of a rotor blade using another foam delivery system,
in accordance with certain embodiments
FIGS. 12-13 are simplified flowcharts illustrating example details
associated with filling a core area of a rotor blade with a solid
foam material using a liquid foam mixture provided in the core
area, in accordance with certain embodiments.
DETAILED DESCRIPTION
The following disclosure describes various illustrative embodiments
and examples for implementing the features and functionality of the
present disclosure. While particular components, arrangements,
and/or features are described below in connection with various
example embodiments, these are merely examples used to simplify the
present disclosure and are not intended to be limiting. It will of
course be appreciated that in the development of any actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developer's specific goals, including compliance
with system, business, and/or legal constraints, which may vary
from one implementation to another. Moreover, it will be
appreciated that, while such a development effort might be complex
and time-consuming; it would nevertheless be a routine undertaking
for those of ordinary skill in the art having the benefit of this
disclosure.
In the Specification, reference may be made to the spatial
relationships between various components and to the spatial
orientation of various aspects of components as depicted in the
attached drawings. However, as will be recognized by those skilled
in the art after a complete reading of the present disclosure, the
devices, components, members, apparatuses, etc. described herein
may be positioned in any desired orientation. Thus, the use of
terms such as `above`, `below`, `upper`, `lower`, `top`, `bottom`,
or other similar terms to describe a spatial relationship between
various components or to describe the spatial orientation of
aspects of such components, should be understood to describe a
relative relationship between the components or a spatial
orientation of aspects of such components, respectively, as the
components described herein may be oriented in any desired
direction. When used to describe a range of dimensions or other
characteristics (e.g., time, pressure, length, temperature) of an
element, operations, and/or conditions, the phrase `between X and
Y` represents a range that includes X and Y.
Additionally, as referred to herein in this Specification, the
terms `forward`, `aft`, `inboard`, and `outboard` may be used to
describe relative relationship(s) between components and/or spatial
orientation of aspect(s) of a component or components. The term
`forward` may refer to a spatial direction that is closer to a
front of an aircraft relative to another component or component
aspect(s). The term `aft` may refer to a spatial direction that is
closer to a rear of an aircraft relative to another component or
component aspect(s). The term `inboard` may refer to a location of
a component that is within the fuselage of an aircraft and/or a
spatial direction that is closer to or along a centerline of the
aircraft (wherein the centerline runs between the front and the
rear of the aircraft) or other point of reference relative to
another component or component aspect. The term `outboard` may
refer to a location of a component that is outside the fuselage of
an aircraft and/or a spatial direction that farther from the
centerline of the aircraft or other point of reference relative to
another component or component aspect.
For convenience, the phrase `FIG. 1" may be used to refer to the
collection of drawings of FIGS. 1A-1B, the phrase "FIG. 3" may be
used to refer to the collection of drawings of FIGS. 3A-3E, etc.
Although certain elements may be referred to in the singular
herein, such elements may include multiple sub-elements. For
example, `a solid foam material" may include one or more solid foam
materials formed using one or more methods described herein.
Further, the present disclosure may repeat reference numerals
and/or letters in the various examples. This repetition is for the
purpose of simplicity and clarity and does not in itself dictate a
relationship between the various embodiments and/or configurations
discussed. Example embodiments that may be used to implement the
features and functionality of this disclosure will now be described
with more particular reference to the accompanying FIGURES.
Referring to FIGS. 1A-1B, FIGS. 1A-1B illustrate perspective views
of an example aircraft, which in this example is a tiltrotor
aircraft 100. Tiltrotor aircraft 100 includes a fuselage 102, a
landing gear 104, a wing 106, a tail member 108, a propulsion
system 110, and a propulsion system 112. The fuselage 102 is the
main body of the tiltrotor aircraft 100, which may include a cabin
(e.g., for crew, passengers, and/or cargo) and/or may house certain
mechanical and electrical components for tiltrotor aircraft 100. In
the illustrated embodiment, tail member 108 may be used as a
vertical and a horizontal stabilizer.
Propulsion system 110 includes a proprotor 120 that includes a
plurality of rotor blades 122. Propulsion system 112 includes a
proprotor 130 that includes a plurality of rotor blades 132.
Various engine(s), gearbox(es), and drive shaft(s) may be provided
in various configurations to provide torque to proprotors 120 and
130. For example, in at least one embodiment, propulsion system 110
may include an engine (not shown) within a nacelle 128 that is
mechanically connected to a one or more gearbox(es) (also not
shown) to provide torque to proprotor 120 and propulsion system 112
may include an engine (not shown) within a nacelle 138 that is
mechanically connected to one or more gearbox(es) (also not shown)
to provide torque to proprotor 130 to provide flight capabilities
(e.g., flight direction, thrust, and/or lift) for tiltrotor
aircraft 100. The position or proprotors 120 and 130, as well as
the pitch of rotor blades 122 and 132, can be selectively
controlled in order to selectively control direction, thrust,
and/or lift of tiltrotor aircraft 100.
For example, the position of proprotors 120 and 130 are moveable
between a helicopter mode and an airplane mode to provide different
types of thrust for tiltrotor aircraft 100. FIG. 1A illustrates
tiltrotor aircraft 100 in helicopter mode in which proprotors 120
and 130 are positioned substantially vertical to provide a lifting
thrust. FIG. 1B illustrates tiltrotor aircraft 100 in an airplane
mode in which proprotors 120 and 130 are positioned substantially
horizontal to provide a forward thrust in which a lifting force is
supplied by wing 106.
Referring to FIG. 2, FIG. 2 illustrates a side view of an example
aircraft, which in this example is a rotorcraft 200. Rotorcraft 200
includes a propulsion system 210, a fuselage 202, landing gear 204,
a tail rotor or anti-torque system 206, an empennage 208, and a
tail structure 212. Anti-torque system 206 may include rotor blades
216. Propulsion system 210 may include one or more engines (not
shown) that is/are mechanically connected to a main rotor gearbox
(not shown) to provide torque to a rotor system 218 that includes
rotor blades 220 and also to provide torque to anti-torque system
206. The pitch of each rotor blade 218 can be managed or adjusted
in order to selectively control direction, thrust, and lift of
rotorcraft 200. The fuselage 202 is the main body of the
rotorcraft, which may include a cabin (e.g., for crew, passengers,
and/or cargo) and/or may house certain mechanical and electrical
components (e.g., engine(s), transmission, and/or flight controls).
In the illustrated embodiment, tail structure 212 may be used as a
horizontal stabilizer.
In some cases, various components of tiltrotor aircraft 100 and/or
rotorcraft 200 may be made from composite materials. For example,
rotor blades 122 and 132 of tiltrotor aircraft 100 and/or rotor
blades 216 and 220 of rotorcraft 200 may be made of composite
materials. A composite material is a combination of different
materials integrated together to achieve certain structural and/or
design properties. Stated differently, a composite material may be
a combination of at least two different materials that, when they
are in close proximity and function in combination with each other,
enhance the capabilities that either material may possess alone.
Composite materials can be integrated together to form
three-dimensional composite structures, such as rotor blades. The
properties of a three-dimensional composite structure are typically
superior to the properties of the underlying materials
individually. For example, certain composite materials may be
lightweight yet relatively strong, rendering them particularly
suitable for aircraft and other applications where weight and/or
strength are critical to performance. In some cases, components may
be made from fiber reinforced composite materials such as carbon
fiber reinforced polymers (CFRPs), boron fiber reinforced
composites, combinations thereof, or the like.
Referring to FIGS. 3A-3E, FIGS. 3A-3E are simplified diagrams
illustrating example details that may be associated with a rotor
blade 300, in accordance with certain embodiments. In particular,
FIG. 3A is a simplified plan view diagram illustrating example
details that may be associated with rotor blade 300 and FIGS. 3B-3D
are simplified cross-sectional, side view diagrams illustrating
other example details associated that may be associated with rotor
blade 300 at various locations of the rotor blade 300. The
cross-section of FIG. 3B is cut along a line generally indicated by
the line labeled `3B` in FIG. 3A. The cross-section of FIG. 3C is
cut along a line generally indicated by the line labeled `3C` in
FIG. 3A. The cross-section of FIG. 3D is cut along a line generally
indicated by the line labeled `3D` in FIG. 3A. The cross-section of
FIG. 3E is cut along a line generally indicated by the line labeled
`3E` in FIG. 3A.
As illustrated in the embodiment of FIG. 3A, rotor blade 300 may
include an inboard end 301 (typically referred to as a root), an
outboard end 302 (typically referred to as a tip), a leading edge
303, and a trailing edge 304. Further as shown in the embodiment of
FIG. 3A, rotor blade 300 may include a spar 305, and an inertia
weight or weight(s) 306. The cross-sections of FIG. 3B-3E may
represent cross-sections at different stations of rotor blade 300.
A `station` corresponds to a particular radial location along a
span 330 of rotor blade 300 and can be identified using a station
number that corresponds to a distance from the inboard end 301 of
rotor blade 300 towards the outboard end 302 of rotor blade 300. In
various embodiments, spar 305, inertia weight(s) 306, and/or other
features of rotor blade 300 may or may not extend across the entire
span 330 of rotor blade 300.
As illustrated in FIGS. 3B-3E, rotor blade 300 may also include an
upper skin 307, a lower skin 308, a trailing edge wedge 309, and a
core area 312. Upper skin 307 may include an inner surface 320a and
an outer surface 320b and lower skin 308 may include an inner
surface 321a and an outer surface 321b. A portion of the upper skin
307 inner surface 320a and a portion of the lower skin 308 inner
surface 321a may be adjacent to the core area 312.
For embodiments described herein, core area 312 is filled with a
solid foam material 314 to provide a core structure for the core
area 312. Solid foam material 314 may be both rigid and flexible to
provide structural strength and/or stiffness for upper and lower
skins 307, 308 to resist inward pressure (generally indicated by
arrows 340, 341) that may be exerted on the rotor blade 300 during
manufacture and/or operation so as to help maintain the designed
geometry of the rotor blade 300. In some embodiments, solid foam
material 314 may be particularly useful to fill and provide
structural strength and/or stiffness in portions of rotor blade 300
where narrow and/or slender geometries of core area 312 may exist.
Features related to methods for filling core area 312 with a solid
foam material 314 are discussed in further detail herein. As
referred to herein in this Specification, the terms `rotor blade`
and `blade` can be used interchangeably.
As shown in FIGS. 3B-3D, some portions of rotor blade 300 may
include a cap 310 and an abrasion strip 311. Spar 305 may be a
structural component provided along at least a portion of the span
330 of rotor blade 300 to provide strength and/or stiffness for
rotor blade 300. Trailing edge wedge 309 may be a structural
component that may aid in bonding the upper skin 307 and the lower
skin 308 together during manufacturing. Spar 305 may have an aft
wall 322 adjacent to the core area 312 and trailing edge wedge 309
may have a forward wall 323 adjacent to the core area 312. In at
least one embodiment, the combination of the upper skin 307 inner
surface 320a, the lower skin 308 inner surface 321a, the spar 305
aft wall 322, and the trailing edge wedge 309 forward wall 323 may
represent an inner mold line (IML), as generally indicated by
dashed-line 333 shown in FIG. 3C.
Cap 310 and abrasion strip 311 may be used to protect the leading
edge 303 of rotor blade 300 from harmful particles (e.g., sand,
dirt, etc.) during operation. Cap 310 may cover leading edge
portions of upper skin 307 and lower skin 308. Abrasion strip 311
may cover portions of cap 310 and leading edge portions of upper
skin 307 and/or lower skin 308 and may taper off. In various
embodiments, a rotor blade (e.g., rotor blade 300) may include
other structural components and/or features such as de-icing
components, attachment components (e.g., for attaching the rotor
blade to a rotor hub), other spars, combinations thereof, or the
like as would be appreciated by one of ordinary skill in the
art.
Rotor blade 300 may have a chord length 331 as measured between the
leading edge 303 and the trailing edge 304. Chord length 331 may
vary along the span 330 of rotor blade 300 as the dimensions of
rotor blade 300 may vary along the span. Rotor blade 300 may also
have a height 332 as measured between the upper skin 307 and the
lower skin 308. Height 332 may also vary along the span 330 of
rotor blade 300 as the dimensions of rotor blade 300 may vary along
the span. The spar 305 and inertia weight 306 may also have varying
dimensions along the span 330 of rotor blade 300, as illustrated in
FIGS. 3B-3E. In various embodiments, the span 330 of rotor blade
300 may vary between 3 feet and 24 feet; however, other spans
(shorter or longer) can be envisioned depending on applications
and/or implementations. For example, rotor blades discussed for
various embodiments described herein may include proprotor/main
rotor blades and/or tail rotor blades.
In various embodiments, any of upper skin 307, lower skin 308,
trailing edge wedge 309, cap 310, and/or abrasion strip 311 may
made of metals (e.g., steel, nickel, titanium, aluminum, etc.),
metal alloys, composite materials, reinforced composite materials
(e.g., carbon fiber reinforced polymers (CFRPs)), fiberglass,
reinforced fiberglass, plastics, reinforced plastics, combinations
thereof, or the like. Note, some of the elements of rotor blade 300
illustrated in FIG. 3B are included in other ones of the
accompanying FIGS.; however, the discussion of some of these
elements may not be repeated when discussing these FIGS. and any of
these elements may take any of the forms disclosed herein.
A rotor blade (e.g., rotor blade 300) is typically designed and
manufactured to meet specific performance targets for a particular
production aircraft (e.g., tiltrotor aircraft, rotorcraft, etc.),
such as targets for strength, rotor inertia, blade vibration, and
blade stability, among others. Conventionally, the core area of a
rotor blade can include a composite or metal honeycomb core
material (e.g., NOMEX.RTM.) or a foam core material (e.g.,
Rohacell.RTM.) that is typically pre-machined within certain
tolerances to fit within the core area of the rotor blade.
Conventional manufacturing of a rotor blade that includes a
honeycomb or foam core material generally involves assembling the
rotor blade components (e.g., upper/lower skins, adhesive films,
spars, weights, core material, trailing edge wedge, etc.) in a
bonding tool, closing the bonding tool around the assembled
components, and bonding the components together under pressure
and/or heat to form the rotor blade. The bonding tool has a fixed
volume when it is closed. Following the bonding, the rotor blade is
typically cured using a curing process that may also include
pressure and/or temperature.
Each of the components of a conventional rotor blade is
manufactured with nominal dimensions within certain design
tolerances. For example, the upper and lower skins may be
manufactured with a nominal shape/thickness/dimensions within a
prescribed+/-degree of tolerance. Similarly, other components such
as the pre-machined core, spar, trailing edge wedge, etc. with
nominal dimension within a prescribed+/-degree of tolerance. As
such, instances may occur in which the variation of tolerance
conditions among the assembled components may cause the overall
volume of the assembled components to be different than the fixed
volume of the bonding tool. For example, if all of the components
are manufactured to their maximum tolerance condition, the bonding
tool may not be completely closed, which can be detrimental to
bonding the components together. Conversely, if all of the
components are manufactured to their minimum tolerance condition,
then there may be gaps between sides of the bonding tool and the
assembled components, which can also be detrimental to bonding the
components together. In another example, tolerance variations among
different components may result in a proper fit in the bonding tool
for some portions of a rotor blade, while resulting in an improper
fit in the bonding tool for other portions of the rotor blade,
which can also be detrimental to bonding the components
together.
Improperly bonded components can cause many problems. For example,
in some cases, improper bonding can cause voids or disbonds to be
present along the bond line between the upper and/or lower skins
and the pre-machined core material, which may result in a lower
quality rotor blade that may be unusable or may need further
machining to repair any problems and can increase the cost and/or
time of manufacturing rotor blades.
A variation in the dimensions of the core material of a given rotor
blade that is to be manufactured is often a contributor to improper
fit of components within a bonding tool. Generally, honeycomb or
foam core materials can be received in pre-manufactured blocks of
material, that need to be machined in-house to the nominal
dimensions for a given rotor blade design. However, current core
machining technology, which often involves carving a
pre-manufactured core block using a 5-axis carving machine, is
often incapable of maintaining the tolerances needed for different
variations in rotor blade geometries. Thus, additional manual
carving/shaping is often needed for pre-manufactured core
materials, which can also increase the cost and/or time of
manufacturing rotor blades.
In some cases, pre-manufactured core materials are bonded to the
blade skins using an intermediate bonding process that occurs
before the overall bonding process. The intermediate bonding
process adds process time and additional tooling. In some cases, a
foam core material can be pre-molded to fit the shape of the core
area; however, use of such pre-molded foam core materials also
utilize an intermediate bonding process that adds process time and
additional tooling. Use of such core materials can be expensive due
to the close tolerances needed for the core structures and tooling
to ensure proper fit into the rotor blade. Additionally, in some
cases an extra cure step may be needed, which further increase cost
and/or time of manufacturing.
Aside from the additional processes, tooling, etc. that may be
needed for using pre-manufactured honeycomb core materials, such
core materials are oriented within the core area of a rotor blade
such that the sides of the honeycomb structures of the core
material are packed together in a horizontal orientation along the
span and chord length of the rotor blade, while the ends of the
honeycomb structures of the core material are (at least partially)
are oriented in contact with the inner surfaces of the upper and
lower skins. [Note if the honeycomb structures were oriented with
the sides of the honeycomb structures in contact with the upper and
lower skins, the structure would be likely to crush under
pressure.] Thus, even under ideal conditions, only a limited
portion of honeycomb core material (e.g., edges of the honeycomb
structures of the material) forms a bond line with the upper and
lower skins.
It is also desirable to provide blade manufacturing methods that
are repeatable and/or certifiable (e.g., by a certifying body or
organization) for manufacturing many different blade types and/or
styles for different types of aircraft. In particular, it is
desirable to provide manufacturing methods in which each
manufactured blade for a given manufacturing method meets certain
quality control criteria. Such quality control criteria may be
desirable to provide for the cost and/or time efficient manufacture
of an aircraft (e.g., as changes beyond tolerances of rotor blades
can affect the design of other aircraft components and/or
integration of the blades with other aircraft components), as well
as to ensure that aircraft meet certain safety guidelines. One
quality control criteria may need to be met may include density
variation of the core structure of rotor blades. For example, a
core density of approximately +/-10% variation across the span of a
blade and across multiple blades of a given design may be one
quality control criteria for a blade manufacturing process. Other
quality control criteria that may need to be met to ensure
repeatable and/or certifiable rotor blade construction may include,
weight, core bond line voids or disbonds, non-destructive
inspection criteria and/or testing, combinations thereof, or the
like.
This disclosure describes various embodiments for providing a
liquid foam mixture in the hollow core area of an assembled rotor
blade. Once provided in the hollow core area, the liquid foam
mixture polymerizes during a polymerization stage. The
polymerization stage is the expansion of the foam from a chemical
reaction of the foam mixture. As the foam expands, it fills the
hollow core area of the rotor blade and also adheres to the exposed
inner surfaces of the upper and lower skins, as well as the inner
walls of the spar and trailing edge wedge. One or more openings may
be provided in the upper skin, the lower skin, and/or the trailing
edge of the rotor blade to allow volatiles to escape during the
polymerization stage, to facilitate a complete and homogeneous fill
of the core area of the rotor blade, and/or to create a desired
pressure within the core area, which can be used, at least in part,
to adjust the density of the expanded foam. Once expanded, the foam
may provide a solid foam material for the rotor blade core
area.
Embodiments described throughout this disclosure that involve using
a liquid foam mixture that expands and becomes a solid foam to fill
the core area of a rotor blade may provide numerous technical
advantages over conventional manufacturing methods that utilize
conventional core materials. One advantage of embodiments herein
may include providing for the ability to fill the core area of a
rotor blade (e.g., once other components of the blade are bonded
together) with an expandable foam using one or more methods, as
discussed herein, that may be more cost and/or time efficient over
conventional core material manufacturing methods. For example,
using a liquid foam mixture that expands and becomes solid foam
within the core area instead of a pre-manufactured or pre-molded
core material may eliminate the extra machining, intermediate
bonding, and/or intermediate curing operations that are typically
utilized for manufacturing blades using conventional core
materials.
Another advantage of embodiments described herein may be that a
liquid foam mixture that expands and becomes a solid foam material
may provide a solid foam core structure for a rotor blade that is
formed in-place within the hollow core area of the blade such that
the solid foam core fills all available space in the core area,
which may prevent voids and/or disbonds between the core structure
and the rotor blade skin(s), the spar aft wall, and the trailing
edge wedge forward wall; thereby providing for a full bond line
between the core structure and surrounding blade components, as
opposed to the limited bond line provided by honeycomb core
materials. Thus, utilizing a liquid foam mixture that expands and
becomes a solid foam in-place within the core area of a blade may
help to eliminate tolerance concerns with the IML as it can expand
to whatever shape, geometry, etc. that the IML may take and can
allow for a wider variety of IML laminate contours without the need
for IML tooling.
Although utilizing a liquid foam mixture that expands and becomes a
solid foam material for the core structure of a blade may provide
numerous technical advantages over blades that utilize conventional
core materials, it can be challenging to utilize a liquid foam
mixture in the manufacture of rotor blades in a manner that is
repeatable and/or certifiable such that multiple rotor blades can
be manufactured to meet certain quality control criteria (e.g.,
density variation, weight, etc.). In particular, it can be
challenging to utilize a liquid foam mixture within the core area
of blades for blades that may have spans up to 24 feet, or more,
and/or may have complex geometries.
Example embodiments associated with forming a solid foam core
structure for a rotor blade utilizing a liquid foam mixture are
described below with more particular reference to the remaining
FIGURES. Although example embodiments discussed herein are
described with reference to tiltrotor aircraft 100 and/or
rotorcraft 200, it should be appreciated that such aircraft are
illustrative of a variety of aircraft in which solid foam core
structures formed utilizing a liquid foam mixture may be used in
accordance embodiments of the present disclosure. Other aircraft in
which a liquid foam mixture may be used can include, for example,
fixed wing airplanes, hybrid aircraft, unmanned aircraft,
gyrocopters, a variety of helicopter configurations, and drones,
among other examples.
Liquid Foam Mixture Features
Features that may be associated with a foam system and liquid foam
mixture that may be used form the solid foam material (e.g., solid
foam material 314) of the core area (e.g., core area 312) for a
rotor blade (e.g., rotor blade 300) are discussed in further detail
with regard to FIGS. 4-6. In at least one embodiment, a foam system
that may be used in the formation of solid foam material 314 may be
a urethane foam system that expands to fill core area 312 of rotor
blade 300. Upon curing, the foam material 314 may be rigid and
flexible, while having a relatively low density. In at least one
embodiment, a urethane foam system that may be used to form solid
foam material 314 may be a polyisocyanurate pourable foam system
marketed under the name of Stepanfoam.RTM., produced by the Stepan
Chemical Company or a polyisocyanurate pourable foam system
marketed under the name JFoam.TM. BX-450, produced by J6 Polymers.
It should be fully appreciated that other foam systems that may be
capable of being provided in the core area of a rotor blade in a
non-solid form may be utilized in accordance with embodiments
described herein.
In at least one embodiment, the foam system may include two
separate resin components, namely a T-component resin 404 (70% by
weight) and an R-component resin 406 (30% by weight). The
T-component resin may be a polymeric MDI and the R-component resin
may be a polyol blend.
In at least one embodiment, the desired weight amounts of
T-component resin 404 and R-component resin 406 may be measured and
poured into a container 402 and may be mechanically agitated to
form a homogenous liquid foam mixture 408, as illustrated in the
embodiment of FIG. 6. In at least one embodiment, a mixer 502 may
be used in rotation in order to mix T-component resin 404 and
R-component resin 406 to form liquid foam mixture 408.
As illustrated in FIG. 5, a mixer 502 may include a shaft 504 and a
plurality of blades 506 in at least one embodiment. In at least one
embodiment, a first set of blades may be located on a first blade
disc 506a and a second set of blades may be located on a second
blade disc 506b. In at least one embodiment, shaft 504 may be
configured to be driven by a drill motor, or the like. In at least
one embodiment, mixer 502 may be rotated at 3500 revolutions per
minute for approximately 10 seconds to 15 seconds when mixing
T-component resin 404 and R-component resin 406 to form liquid foam
mixture 408. In at least one embodiment, once the mixing is
complete, liquid foam mixture 408 may be poured into core area 312
as quickly as possible, as the reaction time for the polymerization
stage of the liquid foam mixture may occur between 40 seconds and
65 seconds. Features related to pouring liquid foam mixture 408
into the core area 312 of rotor blade 300 are discussed further
herein. Although a liquid foam mixture may be poured into the core
area of a rotor blade in some embodiments, other embodiments may
include methods for providing the liquid foam mixture in the core
area using one or more different types of foam delivery systems,
which are also discussed further herein.
Although in some embodiments, the T-component resin 404 and the
R-component resin may be mixed by weight amount, in other
embodiments the T-component resin 404 and the R-component resin may
be mixed by volume amount. The total weight amount of liquid foam
mixture 408 may be at least partially dependent on the desired
density and the volume of a core area 312 that is to be filled with
a solid foam material 314. For example, because density is the
relationship is mass per unit volume, the desired density of a
solid foam material 314 at least partially dictates the weight
amount of the liquid foam mixture 408. However, as discussed
further herein a small portion of the liquid foam mixture 408 may
escape through one or more opening(s) that may be provided about a
core area 312 of a given rotor blade 300 when it is hollow (e.g.,
prior to filling it with the foam), which can also affect the final
density of the solid foam material 314.
In various embodiments, methods described herein may use opening(s)
provided about a core area 312 of a given rotor blade 300 to allow
volatiles to escape during the polymerization of the liquid foam
mixture 408 (typically referred to as `outgassing`), while also
creating a desired pressure within the core area 312 of the given
blade. For example, pressure within a given core area 312 can
inhibit expansion of a liquid foam mixture 408 during the
polymerization process, thereby increasing the density of the solid
foam material 314. As such, the size and number of opening(s) may
be configured so as to selectively tailor the density of a solid
foam material 314 for a given rotor blade 300. In some embodiments,
opening(s) may be provided for a core area 312 of a given rotor
blade 300 to create a solid foam material 314 within the core area
having a density of approximately 12-16 pounds/ft.sup.3. However,
in some embodiments, this size and quantity of opening(s) may be
increased to produce a solid foam material 314 having a lower
density or may be decreased to produce a solid foam material 314
having a higher density.
Other factors may affect the density of a solid foam material 314
for a given rotor blade 300. For example, one factor that may
affect the density of a solid foam material 314 of a given rotor
blade 300 may be the temperature at which the liquid foam mixture
408 is provided in the core area 312 of the given blade. If the
temperature at which the liquid foam mixture 408 is provided in the
core area 312 is below ambient temperature (e.g., lower than 70
degrees Fahrenheit), the liquid foam mixture 408 may be more
viscous and may expand less, which can result in a solid foam
material 314 having an increased density. Conversely, if the
temperature at which the liquid foam mixture 408 is provided in the
core area 312 is at an elevated temperature (e.g., at or above 100
degrees Fahrenheit), the liquid foam mixture 408 may be more
viscous and may expand more, which can result in a solid foam
material 314 having a decreased density. In some embodiments, a
higher temperature liquid foam mixture 408 will increase the
reaction rate of the mixture, giving less time to provide it in the
hollow core area of a given blade but allowing the liquid to flow
more easily and fill the blade faster. Conversely, in some
embodiments, decreasing the temperature will reduce the reaction
rate, giving more time to pour but making the liquid more viscous
and potentially more difficult to fill the hollow core area of a
given blade.
Another factor that may affect the density of a solid foam material
314 for a given rotor blade 300 may be hydrostatic pressure due to
weight of a liquid foam mixture 408. For example, in some
embodiments, a given rotor blade 300 may be tilted along one or
more directions as a liquid foam mixture 408 is provided in the
core area 312 of the given blade. In some embodiments, at least one
of the outboard end 302 and/or the leading or trailing edge 303,
304 of a given rotor blade 300 may be tilted downward as a liquid
foam mixture 408 is provided in the core area 312 of the given
blade. In some embodiments, increasing the downward tilting angle
for a given blade along one or more directions while a liquid foam
mixture is provided in the hollow core area of the blade may allow
the liquid foam mixture to reach tight cavities; whereas decreasing
the tilting angle while providing the liquid foam mixture may help
to ensure the foam provides good coverage for the core area as it
expands.
For embodiments in which a given rotor blade 300 is tilted along
one or more directions, subsequent liquid foam provided in the core
area can push down on previous liquid foam provided in the core
area 312 of the given blade. Hydrostatic pressure that may be
created due to the weight of a liquid foam mixture 408 pushing down
on itself can also increase the density of solid foam material 314.
In various embodiments, the amount of hydrostatic pressure that may
be created for a liquid foam mixture 408 may be adjusted based on
one or more of: the degree(s) and/or direction(s) of tilting of a
given rotor blade 300, the flow rate at which the liquid foam
mixture 408 is provided in the core area 312 of a given rotor blade
300, the location(s) (e.g., station(s) along the span 330 of a
given rotor blade 300) that the liquid foam mixture 408 is provided
in the core area 312 of the given blade, the temperature at which
the liquid foam mixture 408 is provided in the core area 312 of a
given rotor blade 300, the reaction time of the liquid foam mixture
408, combinations thereof, or any other factors that might affect
hydrostatic pressure created by the liquid foam mixture 408. In at
least one embodiment, the degree(s) and/or direction(s) of tilting
a given rotor blade 300 can be relative to a horizontally level
position of the rotor blade along an inboard-outboard axis
(generally represented by arrows 342) and/or a forward-aft axis
(generally represented by arrows 343) in relation to a vertical
axis (generally represented by arrows 344).
Other factors may be considered to adjust the density of a solid
foam material 314 for a given rotor blade 300. For example, in some
embodiments, the density of a solid foam material 314 for a given
rotor blade 300 may be adjusted based, at least in part, on the
expected operational loading of the given rotor blade 300. It is to
be understood that the density of a solid foam material 314 is
preferably customizable in accordance with the specific
implementation and/or application of the solid foam material 314 in
a given rotor blade 300 and may, therefore, be adjusted based on
implementation(s) and/or application(s) in accordance with
embodiments described herein.
Methods for Providing a Liquid Foam Mixture in a Rotor Blade Core
Area
Because rotor blades may vary greatly in span and, in some cases
may have spans up to or greater than 24 feet, it can be challenging
to utilize a liquid foam mixture (e.g., liquid foam mixture 408) in
a manner such that the quality of manufactured rotor blades meets
certain quality control criteria. For example, in some cases,
approximately 15 ounces of a liquid foam mixture may be used to
form a solid foam material for a given rotor blade that may have a
span of 24 feet. Providing such a small volume of liquid foam
mixture (e.g., 15 ounces) within the hollow core area of a blade
that has varying dimensions and extends across a span of 24 feet in
order to form a solid foam material in the core area that has a
density variation of only 10% across the 24 foot span is extremely
challenging. Further, providing a repeatable and/or certifiable
manufacturing method utilizing a liquid foam mixture that results a
10% density variation across multiple 24 foot blades is even more
challenging. Features that may be associated with providing a
liquid foam mixture in a hollow core area of a given rotor blade
are discussed in further detail with regard to FIGS. 7-13.
For example, FIGS. 7A-7C are simplified diagrams illustrating
example details that may associated with forming an example rotor
blade 700 in which the rotor blade has a hollow core area 712 that
can be filled with a foam material, in accordance with certain
embodiments. FIGS. 8A-8D are simplified diagrams illustrating
example details that may be associated with providing a liquid foam
mixture (e.g., liquid foam mixture 408) in a core area 712 of a
given rotor blade 700 using various pouring methods, in accordance
with certain embodiments. FIGS. 9A-9C are simplified diagrams
illustrating example details that may be associated with providing
a liquid foam mixture in a core area 712 of a given rotor blade 700
using a foam delivery system 900, in accordance with certain
embodiments.
FIGS. 10A-10B are simplified diagrams illustrating example details
that may be associated with another example rotor blade 1000 in
which the rotor blade has a core area 1012 that can be filled with
a foam material, in accordance with certain embodiments. FIGS.
11A-11C are simplified diagrams illustrating example details that
may be associated with providing a liquid foam mixture in a core
area 1012 of a given rotor blade 1000 using a foam delivery system
1100, in accordance with certain embodiments. FIGS. 12-13 are
simplified flowcharts illustrating example details associated with
providing a liquid foam mixture in a hollow core area of a rotor
blade, in accordance with certain embodiments.
In at least one embodiment, a rotor blade 700 may include a lower
skin 708, a cap 710, a spar 705, an inertia weight 706, a trailing
edge wedge 709, an upper skin 707, and an abrasion strip 711 that
may be assembled together within a lower bonding tool 741 as shown
in FIG. 7A. An upper bonding tool 740 may be closed over the
assembled components. As illustrated in FIG. 7B, pressure 742 and
heat 743 may be applied in order to bond the components together.
In some embodiments, adhesives and/or adhesive films may be
incorporated to aid in bonding the components together. A hollow
core area 712 is present for the rotor blade 700 after the
components are bonded together. The bonded components may also be
cured using one or more cure cycles that may include elevated
temperature(s) and/or pressure(s) applied to the bonded together
rotor blade 700. Various methods may be used to bond components
together for a given rotor blade as would be appreciated by one of
ordinary skill in the art.
As illustrated in FIG. 7C, rotor blade 700 may include an inboard
end 701, an outboard end 702, a leading edge 703, and a trailing
edge 704. The outboard end 702 may be closed with the upper and
lower skins 707, 708 bonded together. In some embodiments, an
additional wedge (not shown) or trailing edge wedge 709 may extend
between the leading edge 703 and the trailing edge 704 along the
outboard end to facilitate bonding the upper and lower skins for
the rotor blade 700. In some embodiments, the inboard end 701 of
core area 712 may have an opening (732); however, in other
embodiments, the inboard end 701 of core area 712 may be closed. In
various embodiments, rotor blade 700 may have a span 730 up to 24
feet.
As illustrated in FIGS. 8A-8D, at least one method for providing a
liquid foam mixture 408 in a hollow core area 712 of a given rotor
blade 700 may include providing one or more opening(s) at one or
more location(s) along the hollow core area 712 of the given rotor
blade 700 and pouring the liquid foam mixture 408 into the hollow
core area 712 using at least one of the openings to form a solid
foam core 714 for the blade. An axis system is illustrated in FIG.
8C that includes an inboard-outboard axis 842 and a forward-aft
axis 843 in relation to a vertical axis 844.
Referring to FIG. 8A, FIG. 8A is a simplified plan view diagram
illustrating example details that may be associated with a given
rotor blade 700 having a hollow core area 712, in accordance with
certain embodiments. In at least one embodiment, a number of
openings 802 may be provided for the upper skin 707 and may include
one or more pour opening(s) 802a and multiple outgas openings 802b.
In some embodiments, one or more opening(s) 802 may be provided by
drilling or cutting openings 802 through upper skin 707 following
bonding together components of a given rotor blade 700. In still
some embodiments, one or more opening(s) 802 may be provided by
drilling or cutting openings 802 through upper skin 707 prior to
bonding together components of a given rotor blade 700.
In various embodiments, outgas openings 802b may have a diameter
ranging between 0.010 inches and 0.0030 inches, however, other
diameters can be envisioned. In some embodiments, outgas openings
802b may be provided at intervals between 12 inches and 36 inches
along the span 730 of a given rotor blade depending on the desired
density for the solid foam material for the given rotor blade;
however, other intervals can be envisioned, depending on the
desired density for the solid foam material for the given rotor
blade.
In some embodiments, pour opening(s) 802a may have a circular
diameter `D.sub.C` (FIG. 8B). In some embodiments, pour opening(s)
802a may be elongated along the inboard-outboard axis 842 to have
an inboard-outboard diameter `D.sub.IO` (FIG. 8B). For example, in
some embodiments, the outboard end 702 of a given rotor blade 700
may be tilted downward between 15 degrees and 75 degrees (relative
to vertical axis 844) to enable gravity to pull the liquid foam
mixture 408 downward toward the outboard end 702 of rotor blade
700. In such embodiments, pour opening(s) 802a may have an
elongated inboard-outboard diameter D.sub.IO, which may help to
avoid pouring liquid foam mixture 408 on and/or to avoid it
touching upper skin 707 when the outboard end 702 may be tilted
downward during the pouring.
In still some embodiments, pour opening(s) 802a may be elongated
along the forward-aft axis 843 to have a forward-aft diameter
`D.sub.FA` (FIG. 8B). For example, in some embodiments, the leading
edge 703 of a given rotor blade 700 may be tilted downward between
15 degrees and 75 degrees (relative to vertical axis 844) to enable
gravity to pull the liquid foam mixture 408 toward the leading edge
of rotor blade 700. Similar to the inboard-outboard diameter, the
forward-aft diameter D.sub.FA may help to avoid pouring liquid foam
mixture 408 on and/or to avoid it touching upper skin 707 when the
leading edge 703 may be tilted downward during the pouring.
In still some embodiments, pour opening(s) 802a may be elongated
along both the inboard-outboard axis 842 and the forward-aft axis
843 to have a half-circle radius `R.sub.HC` (FIG. 8B). For example,
in some embodiments, any combination of the outboard end 702 and/or
the leading edge 703 may be tilted downward to enable gravity to
pull liquid foam mixture 408 toward the outboard end 702 and/or the
leading edge 703 during the pouring.
In various embodiments, the diameter (e.g., D.sub.C, D.sub.IO,
D.sub.FA) or radius (e.g., R.sub.HC) of pour opening(s) 802a may be
several inches, or more. For example, in some embodiments, a larger
diameter and/or radius for pour opening(s) 802a may be used when a
larger tilting angle alpha (a) (as shown in FIG. 8C) may be used
during the pouring in comparison to smaller tilting angle pours,
which may have a smaller diameter and/or radius.
In some embodiments, pour opening(s) 802a may be located at a
distance 734 (e.g., at a station) along span 730 that may be
associated with a center of volume (sometimes referred to as
`volumetric split`) for the fixed volume of hollow core area 712.
As discussed herein, the dimensions of the core area 712 may vary
between the inboard end 701 and the outboard end 702 (e.g., the
core area 712 may be larger at the inboard end than at the outboard
end) such that the center of volume for the core area may be
located off-center from the center of span 730. In still some
embodiments, the fixed volume of the hollow core area 712 of a
given rotor blade 700 may be calculated and may be sub-divided into
a number of respective sub-volumes, in which case a respective pour
opening 802a may be provided at a respective distance along the
span 730 relative to the volumetric split of each respective
sub-volume. Other variations relating to pouring a liquid into a
hollow core area of a rotor blade can be envisioned in accordance
with embodiments described herein. Variations related to pouring a
liquid foam mixture in a hollow core area of a rotor blade may be
provided to attain a desired density and/or density variation of a
solid foam material in the core area of a rotor blade.
Referring to FIG. 8C, in at least one embodiment, a liquid foam
mixture 408 may be poured (as generally illustrated by arrow 850)
through a pour opening 802a having an elongated inboard-outboard
diameter (D.sub.IO) while the outboard end 702 of rotor blade 700
may be tilted (as generally illustrated by arrow 860) downward at a
tilt angle alpha (.alpha.). Gravity may pull the liquid foam
mixture 408 downward (as generally illustrated by arrow 851) toward
the outboard end 702. Liquid foam mixture 408 polymerizes and
expands to fill the core area 712 with a solid foam material 714.
Expansion of the liquid foam mixture 408 and/or expanding foam may
be pushed upward (as generally illustrated by arrow 853) toward the
inboard end 701 of rotor blade 700 to fill core area with solid
foam material 714. In some embodiments, liquid foam mixture 408 may
be heated or cooled. In some embodiments, the tilt angle alpha
(.alpha.) of the rotor blade may be varied during the pouring
(850). Other variations may be provided to adjust the density of
solid foam material 714, as discussed for various embodiments
described herein.
FIG. 8D is a side, cross-sectional view diagram (cut along a line
generally indicated by the line labeled `8D` in FIG. 8C) of rotor
blade 700 illustrating solid foam material 714. Solid foam material
714 may completely fill core area 712 and may adhere to the inner
surface of the upper and lower skins 707, 708 as well as to the aft
wall of spar 705 and the forward wall of trailing edge wedge 709.
In some embodiments, solid foam material 714 may be cured using one
or more cure cycles, which may include one or more elevated
temperatures.
Some of the solid foam material 714 may escape one or more
opening(s) 802 during polymerization. In some embodiments, excess
foam material that may have escaped from one or more opening(s)
during polymerization may be removed and the opening(s) may be
sealed using known methods as would be appreciated by one of
ordinary skill in the art. For example, in some embodiments,
opening(s) 802 may be patched using composite materials that may be
laid up over the holes, bonded to the upper skin, sanded, etc.
Although example features discussed in FIGS. 8A-8D are discussed
with reference to opening(s) 802 provided in the upper skin 707 of
a given rotor blade 700, it is to be understood that openings may
be provided in the lower skin 708 in lieu of the upper skin 707 and
a liquid foam mixture 408 may be provided in the hollow core area
712 in a similar manner as discussed for the embodiments of FIGS.
8A-8D.
Referring to FIGS. 9A-9C, in some embodiments, a liquid foam
mixture 908 may be provided in the core area 712 of a given rotor
blade 700 using a foam delivery system 900. FIG. 9A is a simplified
schematic diagram illustrating details that may be associated with
foam delivery system 900, in accordance with certain embodiments.
In at least one embodiment, foam delivery system 900 may include a
motor 901, a metered mixing system 904, a first pump 910 and a
first reservoir 911, a second pump 920 and a second reservoir 921,
and a control system 930. In at least one embodiment, metered
mixing system 904 may include a housing 905 in which a spiral auger
or worm gear 906 may be provided that may be connected to a
rotating shaft 903 (within a protective covering 902) that may be
in mechanical communication with motor 901. The metered mixing
system 904 may further include one or more nozzle(s) 907. In at
least one embodiment, control system 930 may be in communication
with motor 901, first pump 910, second pump 920, and metered mixing
system 904 via communication links 931, which may enable electronic
communications between the components. In at least one embodiment,
control system 930 may be in communication with a computing system
970 via a network 940. Also shown in FIG. 9A is a user 960.
In various embodiments, communication links 931 can include wired
(e.g., serial, parallel, Ethernet, etc.) and/or wireless (e.g.,
Bluetooth.TM., WiFi, etc.) communication links. In various
embodiments, foam delivery system 900 may also include various
sensors (e.g., pressure, flow rate, temperature, etc.), valves,
heating elements, cooling elements, combinations thereof, or the
like, which are not shown but would be appreciated by one of
ordinary skill in the art to facilitate various features described
herein.
In at least one embodiment, foam delivery system 900 may provide
for mixing together a prescribed amount of a T-component resin 924
and an R-component resin 926 to form a liquid foam mixture 908 that
may be injected into a hollow core area 712 of a given rotor blade
700. During operation, for example, pump 910 may pump T-component
resin 924 from first reservoir 911 (via a hose 912) into metered
mixing system 904 (via a hose 913). Pump 920 may pump R-component
resin 926 from second reservoir 921 (via a hose 922) into metered
mixing system 904 (via a hose 923). Auger 906 may be rotated via
motor 901 and shaft 903 at a given rotations per minute to mix
T-component resin 924 and R-component resin 926 to form liquid foam
mixture 908 within housing 905 and push the liquid foam mixture
through nozzle(s) 907.
Control system 930 may control the amount of T-component resin 924
and R-component resin 926 that are pumped into metered mixing
system 904. For example, in at least one embodiment, in-line valves
(not shown) for hoses 913, 923 may be selectively opened and closed
to control the amount of resin input to metered mixing system 904.
Consider an example in which it may be determined that a particular
weight amount of liquid foam mixture 908 may be used to form a
solid foam material for a core area 712 of a given rotor blade 700
having a particular volume. For the present example, consider that
a user 960 sets a weight amount of liquid foam mixture 908 to be
2.7 pounds for the core area of the given rotor blade 700. In this
example, user 960 may input the weight amount via computing system
970, which may communicate the amount to control system 930. In
turn, control system 930 may determine the appropriate amounts of
T-component resin 924 and R-component resin 926 by weight (e.g.,
70%/30%) to input into metered mixing system 904 and may control
the operation of first and second pumps 910, 920 to facilitate to
input the appropriate amounts of resin into metered mixing system
904. Control system 930 may also control the operation of motor 901
(e.g., the speed of auger 906) to control the flow rate of liquid
foam mixture 908 through nozzle(s) 907.
Hoses 912, 913, 922, and 923 as well as shaft 903/covering 902 may
have any suitable dimensions. For example, in some embodiments, the
length of hoses 913 and 923 as well as shaft 903/covering 902 may
have a length that is suitable to insert metered mixing system into
a hollow core area 712 of a given rotor blade 700 that may have a
span up to 24 feet or more, depending on the span of the given
rotor blade 700.
Referring to FIG. 9B, FIG. 9B is a simplified block diagram
illustrating example details that may be associated with control
system 930. In at least one embodiment, control system 930 may
include at least one processor(s) 932, at least one memory
element(s) 933, and input/output (I/O) device(s) 934. At least one
processor(s) 932 can be at least one hardware processor(s) that
uses software, firmware, combinations thereof, or the like to
execute operations. At least one memory element(s) 933 can store
instructions that, when executed, cause processor(s) 932 to carry
out one or more operation(s). In various embodiments, I/O device(s)
may include display devices (e.g., a plasma display panel (PDP), a
liquid crystal display (LCD), a light emitting diode (LED) display,
a cathode ray tube (CRT), etc.), a keyboard, a touch screen, a
mouse, a trackball, voice recognition, touch pad, etc. that may
allow a user (e.g., user 960) to interact with control system 930.
In some embodiments, I/O devices may include Ethernet ports, serial
ports, parallel ports, wireless controllers, combinations thereof,
or the like that may allow a user (e.g., user 960) to interact with
control system 930 via one or more communication link(s) 931 (e.g.,
via network 940 and computing system 970).
Control system 930 may also include one or more buses, such as a
system bus and a memory bus, collectively represented by a bus 935,
for enabling communications between components of control system
930. Processor(s) 932, which may also be referred to as a central
processing unit (CPU), can include any general or special purpose
processor capable of executing machine-readable instructions and
performing operations on data as instructed by the machine-readable
instructions. A memory element 933 may be directly accessible by
the hardware processor for accessing machine-readable instructions
and may be in the form of random access memory (RAM) or any type of
dynamic storage (e.g., dynamic random-access memory (DRAM)).
Control system 930 may also include non-volatile memory, such as a
hard disk, that is capable of storing electronic data including
executable software files. In some embodiments, externally stored
electronic data may be provided to control system 930 through one
or more removable media drives, which may be configured to receive
any type of external media such as compact discs (CDs), digital
video discs (DVDs), flash drives, external hard drives, etc.
As used herein, the term `removable media drive` refers to a drive
configured to receive any type of external computer-readable media.
Instructions embodying activities, functions, operations, etc.
described herein may be stored on one or more external and/or
internal computer-readable media. Additionally, such instructions
may also, or alternatively, reside at least partially within a
memory element (e.g., in main memory or cache memory of
processor(s) 932 during execution, or within a non-volatile memory
element(s) (e.g., one or more memory element(s) 933) of control
system 930. Accordingly, other memory element(s) 933 of control
system 930 may also constitute computer-readable media. As referred
to herein in this Specification, the term `computer-readable
medium` is meant to include any non-transitory computer-readable
storage medium (e.g., embedded logic provided in an application
specific integrated circuit (ASIC), in digital signal processing
(DSP) instructions, software [potentially inclusive of object code
and source code], etc.) that is capable of storing instructions for
execution by control system 930 (e.g., by one or more processor(s)
932) that causes the system to perform any of one or more of the
activities, functions, operations, etc. disclosed herein.
In various embodiments, the at least one processor(s) 932 can
execute instructions to perform operations to determine, adjust,
etc. one of more of: an amount of T-component resin 924 to input to
metered mixing system 904, an amount of R-component resin 926 to
input to metered mixing system 904, flow rate(s) of a liquid foam
mixture 908, temperature(s) of a liquid foam mixture 908,
combinations thereof, or the like, in accordance with various
embodiments.
Various communications between computing system 970 and control
system 930 may occur across a network, such as network 940. Network
940 may represent any number and combination of wireline and/or
wireless networks suitable for data transmission. Network 940 may,
for example, communicate internet protocol packets, frame relay
frames, asynchronous transfer mode cells, and/or other suitable
data between network addresses. Network 940 may include a public or
private data network; one or more intranets; a local area network
(LAN); a metropolitan area network (MAN); a wide area network
(WAN); a wireline or wireless network; a local, regional, or global
communication network; an optical network; a satellite network; a
cellular network; an enterprise intranet; all or a portion of the
Internet; other suitable communication links; or any combination of
the preceding. Although the illustrated embodiment shows one
network 940, teachings of certain embodiments recognize that more
or fewer networks may be used and that not all elements may
communicate via a network. Teachings of certain embodiments also
recognize that communications over a network is one example of a
mechanism for communicating between parties, and any suitable
mechanism may be used.
In at least one embodiment, computing system 970 may include
processor(s), memory element(s) I/O device(s), and buses. In other
embodiments, computing system 970 may include more, less, or other
components. Computing system 970 may be operable to perform one or
more operations of various embodiments. Although embodiments
discussed herein provide one example of computing system 970 that
may be used with other embodiments, such other embodiments may
utilize computing systems other than computing system 970.
Additionally, embodiments may also employ multiple computing
systems 970 or other computing systems networked together in one or
more public and/or private computer networks, such as one or more
networks 940.
Users 980 may include any individual, group of individuals, entity,
machine, and/or mechanism that interacts with control system 930
and/or computing system 970. Examples of users 980 may include, but
are not limited to, a pilot, service person, engineer, technician,
contractor, agent, human operator, and/or employee. Users 980 may
be associated with an organization. An organization may include any
social arrangement that pursues collective goals. One example of an
organization is a business. A business is an organization designed
to provide goods or services, or both, to consumers, governmental
entities, and/or other businesses.
Referring to FIG. 9C, FIG. 9C is a simplified schematic diagram
illustrating example details associated with filling a core area
712 of a given rotor blade 700 utilizing foam delivery system 900,
in accordance with certain embodiments. One or more outgas openings
942 may be provided for the given rotor blade 700. In at least one
embodiment, metered mixing system 904 (including hoses, etc.) may
be inserted into the opening 732 (as shown in FIG. 7C) at the
inboard end 701 of the rotor blade 700 to a distance associated
with the span 730 of the given rotor blade 700 to provide a liquid
foam mixture 908 within the core area 712. The given rotor blade
700 can be tilted along the inboard-outboard axis and/or the
forward-aft axis (e.g., as discussed in FIG. 8C) for one or more
tilt angles (.alpha.) as the liquid foam mixture 908 is provided in
the core area 712.
In at least one embodiment, the distance that the metered mixing
system 904 may be inserted into the opening 732 may be located at a
distance 734 along span 730 that may be associated with a
volumetric split for the fixed volume of the core area 712. Once
inserted to a given distance, foam delivery system 900 via metered
mixing system 904 may provide the liquid foam mixture 908 in the
hollow core area 712 by injecting (as generally shown by arrow 950)
the liquid foam mixture 908 via one or more nozzle(s) 907. For
embodiments in which the blade 700 is tilted downward along the
inboard-outboard axis, gravity will pull the liquid foam mixture
downward (as generally shown by arrow 951) toward the outboard end
702. The liquid foam mixture 908 polymerizes and expands to fill
the core area 712 with a solid foam material 914. Liquid foam
mixture 908 and/or expanding foam may be pushed upward (as
generally illustrated by arrow 952) toward the inboard end 701 of
rotor blade 700 to fill core area 712 with solid foam material 914.
As the liquid foam mixture 908 is injected (950) the metered mixing
system 904 may be removed (as generally shown by arrow 954) from
the opening and/or the rotor blade 700 may be moved away (as
generally shown by arrow 955) from the metered mixing system 904.
In some embodiments, the rate at which the metered mixing system
904 is removed from the opening may be varied using one or more
rates and/or the rate that the rotor blade 700 is moved away from
the metered mixing system 904 may be varied using one or more
rates. Foam delivery system 900 may stop the injecting once a
prescribed amount of liquid foam mixture 908 has been provided in
the core area.
In some embodiments, the location of metered mixing system 904 at
distance 734 may be maintained for a period of time before it is
moved outward from the core area (e.g., by moving one or both of
the mixing system and/or the rotor blade). In still some
embodiments, metered mixing system 904 may be inserted to a first
distance (e.g., a distance 737) located proximate to the outboard
end 702 of a given rotor blade 700 and moved outward toward the
inboard end 701 of the rotor blade during the injecting. In still
some embodiments, may be inserted to a first distance (e.g., a
distance 737) located proximate to the outboard end 702 of a given
rotor blade 700 and moved outward toward the inboard end 701 of the
rotor blade during the injecting to one or more other distances
(e.g., distances 736, 735, 734, 733, etc.). In some embodiments,
moving the metered mixing system 904 to one or more distances may
include holding its position at the one or more distances for one
or more periods of time in which the periods of time may be the
same or different. In some embodiments, the flow rate for the
liquid foam mixture 908 may be varied using one or more flow rates
during the injecting (950). In still some embodiments, the fixed
volume of the hollow core area 712 may be calculated and may be
sub-divided into a number of sub-volumes, in which case distance(s)
at which the metered mixing system 904 may be provided may
correspond to distance(s) along the span 730 relative to the
volumetric split of each respective sub-volume. Other variations
relating to injecting a liquid foam mixture in the core area of a
rotor blade can be envisioned in accordance with embodiments
described herein. Variations related to utilization of a foam
delivery system 900 to inject a liquid foam mixture in a hollow
core area of a rotor blade may be provided to attain a desired
density and/or density variation of a solid foam material in the
core area of a rotor blade in accordance with various
embodiments.
In some embodiments, liquid foam mixture 908 may be heated or
cooled during the injecting (950). In some embodiments, the tilt
angle alpha (.alpha.) of a given rotor blade along one or more axes
may be varied during the injecting (950). In some embodiments,
excess foam material that may have escaped from one or more outgas
openings 942 during polymerization may be removed and the
opening(s) may be sealed using known methods as would be
appreciated by one of ordinary skill in the art.
In various embodiments, providing a liquid foam mixture in the
hollow core area of a rotor blade using a foam delivery system and
metered mixing system that is inserted through an opening at the
inboard end of a rotor blade provides numerous advantages for
manufacturing rotor blades. In particular, one advantage of
embodiments described herein may include providing methods that may
be repeatable and/or certifiable in order meet various quality
control criteria for manufacturing many different blade types
and/or styles for many different types of aircraft.
Referring to FIGS. 10A-10B, FIGS. 10A-10B are simplified diagrams
illustrating example details that may be associated with another
example rotor blade 1000 in which the rotor blade has a core area
1012 that can be filled with a foam material, in accordance with
certain embodiments. FIG. 10A is a simplified perspective view
diagram illustrating example details that may be associated with a
rotor blade 1000, in accordance with certain embodiments. FIG. 10B
is a simplified perspective view of a portion of rotor blade 1000.
Rotor blade may include an inboard end 1001, an outboard end 1002,
a leading edge 1003, a trailing edge 1004, and a hollow core area
1012. In some embodiments, core area 1012 may be open at the
inboard end 1001; however, in some embodiments, core area 1012 may
be closed at the inboard end 1001.
In some embodiments, one or more port(s) 1060 may be provided for
one or more opening(s) 1042 provided along a span 1030 of rotor
blade 1000. In various embodiments, openings 1042 may include one
or more outgas opening(s) 1042b provided in the upper skin of the
rotor blade 1000 and one or more injection opening(s) 1042a
provided along the trailing edge 1004 of the rotor blade 1000 in
which a port 1060 may be provided for each injection opening 1042a.
In some embodiments, outgassing may also be provided via opening(s)
1042a and port(s) 1060.
Port(s) 1060 may be configured to attach a hose from a foam
delivery system (e.g., a foam delivery system 1100, as discussed in
FIGS. 11A-11C) in order to inject a liquid foam mixture into the
core area 1012. Thus, port(s) 1060 may include any structural
features that may facilitate connecting and disconnecting a hose
thereto. In at least one embodiment, opening(s) 1042a may be
provided via the trailing edge wedge (not labeled) for the rotor
blade 1000 and the upper and/or lower skins (not labeled) may have
portions removed (before or after bonding) that exposes the
openings 1042a. In at least one embodiment, port(s) 1060 may be
configured to be removable following injection of a liquid foam
mixture in the core area and the portions of the upper and/or lower
skins may be patched or otherwise repaired, as would be appreciated
by one of ordinary skill in the art.
In some embodiments, an opening 1042a and port 1060 may be provided
at distance (e.g., a distance 1034) along the span 1030 that may be
associated with a volumetric split for the fixed volume of the core
area 1012. Although one opening/port 1042a/1060 is illustrated in
FIGS. 10A-10B, it is to be understood that any number of
openings/ports may be provided in order to inject a liquid foam
mixture at any station along the span 1030 of a given rotor blade.
For example, in some embodiments, the fixed volume of the hollow
core area 1012 of a given rotor blade may be calculated and may be
sub-divided into a number of respective sub-volumes, in which case
a respective opening/port 1042a/1060 may be provided at a
respective distance along the span 1030 relative to the volumetric
split of each respective sub-volume. Other variations relating to
opening/port location, injection process(es), etc. can be
envisioned in various embodiments. For example, in some
embodiments, port(s) may be provided along the upper and/or lower
skin(s) of a given rotor blade in addition to or in lieu of
providing port(s) along the trailing edge of the blade. Variations
(e.g., temperature, tilting, etc.) related to utilization of a foam
delivery system 1100 to inject a liquid foam mixture in a hollow
core area of a rotor blade may be provided to attain a desired
density and/or density variation of a solid foam material in the
core area of a rotor blade in accordance with embodiments described
herein.
Referring to FIGS. 11A-11C, in some embodiments, a liquid foam
mixture may be provided in the core area 1012 of a given rotor
blade 1000 using a foam delivery system 1100. FIG. 11A is a
simplified schematic diagram illustrating details that may be
associated with foam delivery system 1100, in accordance with
certain embodiments. In at least one embodiment, foam delivery
system 1100 may include a motor 1101, a metered mixing system 1104,
a first pump 1110 and a first reservoir 1111, a second pump 1120
and a second reservoir 1121, and a control system 1130. In at least
one embodiment, metered mixing system 1104 may include a housing
1105 in which a spiral auger or worm gear 1106 may be provided that
may be connected to a rotating shaft 1103 (within a protective
covering 1102) that may be in mechanical communication with motor
1101. The metered mixing system 1104 may further include one or
more hose(s) 1107 in which each respective hose 1107 may include a
respective attachment fitting 1109. In some embodiments, attachment
fitting(s) 1109 may be configured to be connected and disconnected
from port(s) 1060 provided for a given rotor blade 1000; however,
in other embodiments, attachment fittings 1109 may be configured to
be inserted in openings provided for a given rotor blade without
the use of ports provided for the given rotor blade.
In at least one embodiment, control system 1130 may be in
communication with motor 1101, first pump 1110, second pump 1120,
and metered mixing system 1104 via communication links 1131, which
may enable electronic communications between the components. In at
least one embodiment, control system 1130 may be in communication
with a computing system 1170 via a network 1140. Also shown in FIG.
11A is a user 1180.
In various embodiments, communication links 1131 can include wired
(e.g., serial, parallel, Ethernet, etc.) and/or wireless (e.g.,
Bluetooth.TM., WiFi, etc.) communication links. In various
embodiments, foam delivery system 1100 may also include various
sensors (e.g., pressure, flow rate, temperature, etc.), valves,
heating elements, cooling elements, combinations thereof, or the
like, which are not shown but would be appreciated by one of
ordinary skill in the art to facilitate various features described
herein. Various hoses interconnecting components of foam delivery
system 1100 are not labeled for sake of brevity.
In at least one embodiment, foam delivery system 1100 may provide
for mixing together a prescribed amount of a T-component resin 1124
and an R-component resin 1126 to form a liquid foam mixture 1108
that may be injected into a hollow core area 1012 of a given rotor
blade 1000. During operation, for example, pump 1110 may pump
T-component resin 1124 from first reservoir 1111 into metered
mixing system 1104. Pump 1120 may pump R-component resin 1126 from
second reservoir 1121 into metered mixing system 1104. Auger 1106
may be rotated via motor 1101 and shaft 1103 at a given rotations
per minute to mix T-component resin 1124 and R-component resin 1126
to form liquid foam mixture 1108 within housing 1105 and push the
liquid foam mixture through nozzle(s) 1107.
Control system 1130 may control the amount of T-component resin
1124 and R-component resin 1126 that are pumped into metered mixing
system 1104. For example, in at least one embodiment, in-line
valves (not shown) for hoses connected to housing 1105 may be
selectively opened and closed to control the amount of resin input
to metered mixing system 904. Components of foam delivery system
may have any suitable dimensions.
In general, features and/or operations that may be performed by
foam delivery system 1100 may be similar to features and/or
operations that may be provided by foam delivery system 900;
however, metered mixing system 1104 may inject a liquid foam
mixture 1108 into the core area of a given blade via one or more
hoses 1107 using one or more openings and/or ports provided for the
blade rather than being inserted in the hollow core area of a given
rotor blade as discussed for metered mixing system 904.
Referring to FIG. 11B, FIG. 11B is a simplified block diagram
illustrating example details that may be associated with control
system 1130. In at least one embodiment, control system 1130 may
include at least one processor(s) 1132, at least one memory
element(s) 1133, I/O device(s) 1134, and a bus 1135. In various
embodiments, at least one processor(s) 932 may have any features of
any other processors (e.g., processor(s) 932) discussed herein; at
least one memory element(s) 1133 may have any features of any other
memory element(s) (e.g., memory element(s) 1134) discussed herein;
I/O device(s) 1134 may have any features of any other I/O devices
(e.g., I/O device(s) 934) discussed herein; and/or bus 1135 may
have any feature(s) of any other buses (e.g., bus 935) discussed
herein.
In various embodiments, the at least one processor(s) 1132 can
execute instructions to perform operations to determine one of more
of: an amount of T-component resin 1124 to input to metered mixing
system 1104, an amount of R-component resin 1126 to input to
metered mixing system 1104, flow rate(s) of a liquid foam mixture
1108, combinations thereof, or the like, in accordance with various
embodiments.
Various communications between computing system 1170 and control
system 1130 may occur across a network, such as network 1140. In
various embodiments, computing system 1170 may have any features of
any other computing systems (e.g., computing system 930) discussed
herein; network 1140 may have any features of any other network
(e.g., network 940) discussed herein; and users 1180 may have any
other features of any other users (e.g., users 980) discussed
herein.
Referring to FIG. 11C, FIG. 11C is a simplified schematic diagram
illustrating example details associated with filling a core area
1012 of a given rotor blade 1000 utilizing foam delivery system
1100, in accordance with certain embodiments. One or more outgas
opening(s) 1042b and one or more respective injection opening(s)
1042a and respective port(s) 1060 may be provided for the given
rotor blade 1000. In at least one embodiment, a hose 1107 of
metered mixing system 1100 may be connected to a given port 1060 of
rotor blade 1000 via an attachment fitting 1109 of the hose 1107 to
provide a liquid foam mixture 1108 within the core area 1012. In
some embodiments, port(s) 1060 and attachment fitting(s) 1109 may
be configured as cam-and-groove couplings to provide a quick
disconnect system for connecting and disconnecting hose(s) 1107
from port(s); however, in other embodiments, port(s) 1060 and
attachment fitting(s) 1109 may be configured with any suitable
features to facilitate connections. The given rotor blade 1000 can
be tilted along the inboard-outboard axis and/or the forward-aft
axis (e.g., as discussed in FIG. 8C) for one or more tilt angles
(.alpha.) as the liquid foam mixture 1008 is provided in the core
area 1012.
As illustrated in the embodiment of FIG. 11C, foam delivery system
1100 via metered mixing system 1104 may provide the liquid foam
mixture 1108 in the core area 1012 by injecting (as generally shown
by arrow 1150) the liquid foam mixture 1108 via one or more hose(s)
1107 connected to one or more port(s) 1060 of rotor blade 1000. For
embodiments in which the blade 1000 is tilted downward along the
inboard-outboard axis, gravity will pull the liquid foam mixture
downward (as generally shown by arrow 1151) toward the outboard end
1002. The liquid foam mixture 1008 polymerizes and expands to fill
the core area 1012 with a solid foam material 1114. Liquid foam
mixture 1108 and/or expanding foam may be pushed upward (as
generally illustrated by arrow 1152) toward the inboard end 1001 of
rotor blade 1000 to fill core area 1012 with solid foam material
1114. Foam delivery system 900 may stop the injecting once a
prescribed amount of liquid foam mixture 1008 has been provided in
the core area. In at least one embodiment, hose(s) 1107 may be
disconnected from port(s) 1060 to allow outgassing for the
expanding foam.
In some embodiments, liquid foam mixture 1108 may be heated or
cooled during the injecting (1150). In some embodiments, the tilt
angle alpha (.alpha.) of a given rotor blade along one or more axes
may be varied during the injecting (1150). In some embodiments,
excess foam material that may have escaped from one or more outgas
openings 1002b and/or port(s) 1060 during polymerization may be
removed and the opening(s) may be sealed using known methods as
would be appreciated by one of ordinary skill in the art. In at
least one embodiment, port(s) 1060 may be removed and corresponding
portions of the upper and lower skin at the location(s) of the
port(s) may be patched or otherwise repaired along the trailing
edge 1004 of the rotor blade.
Although ports and attachment fittings are described as a means for
connecting hoses of metered mixing system 1100 to openings of a
given rotor blade, it should be appreciated that any means may be
used to connect hoses to one or more openings of a rotor blade. For
example, in some embodiments, any combination and/or number of
hose(s) 1107 may be configured with elastomeric fittings,
spring-loaded clips, or the like that may be inserted into
opening(s) and/or coupled to port(s) that may be provided anywhere
proximate to the hollow core area of a rotor blade (e.g., in the
upper skin, the lower skin, along the trailing edge, through the
aft wall of the spar, etc.) to inject a liquid foam mixture into
the core area and then removed to allow outgassing. The examples
discussed herein are only a few of the many possible means that may
be used for providing a liquid foam mixture in a hollow core area
of a rotor blade and are not meant to limit the broad scope of the
present disclosure. Virtually any other connections may be used
using similar means and methods as those described herein and,
thus, are clearly within the scope of the present disclosure.
In various embodiments, providing a liquid foam mixture in the
hollow core area of a rotor blade using a foam delivery system and
metered mixing system that is connected to opening(s) of a rotor
blade provides numerous advantages for manufacturing rotor blades.
In particular, one advantage of embodiments described herein may
include providing methods that may be repeatable and/or certifiable
in order meet various quality control criteria for manufacturing
many different blade types and/or styles for many different types
of aircraft.
Referring to FIG. 12, FIG. 12 is a simplified flowchart 1200
illustrating example details that may be associated with filling a
hollow core area of a given rotor blade with a solid foam material
using a liquid foam mixture provided in the core area of the rotor
blade using a foam delivery system inserted through an opening at
an inboard end of the rotor blade, in accordance with certain
embodiments. In at least one embodiment, flowchart 1200 may begin
at block 1202 by providing one or more outgas openings for the
hollow core area of the rotor blade. The flowchart may proceed to
1204 by positioning one or more nozzle(s) (e.g., via a metered
mixing system) within the hollow core area at a distance associated
with a span of the rotor blade (e.g., a station along the span).
The flowchart may proceed to 1206 by providing a liquid foam
mixture in the hollow core area in which the liquid foam mixture
expands and becomes a solid foam material that fills the hollow
core area of the rotor blade. The flowchart may proceed to 1208 by
moving the nozzle(s) and/or the rotor blade to remove the nozzle(s)
from the core area as the liquid foam mixture is provided in the
core area. The flowchart may proceed to 1210 by curing the solid
foam material. The flowchart may proceed to 1212 by sealing the
outgas opening(s). It is to be understood that different variations
may be provided for the flowchart 1200 in accordance with various
embodiments described herein (e.g., positioning the nozzle(s) at
different distance(s), heating/cooling the liquid foam mixture,
adjusting the flow rate of the liquid foam mixture, tilting the
rotor blade, etc.). In at least one embodiment, the flowchart may
be completed following the curing at 1210. In some embodiments,
however, the flowchart may restart and/or certain blocks may be
repeated.
Referring to FIG. 13, FIG. 13 is a simplified flowchart 1300
illustrating example details that may be associated with filling a
hollow core area of a given rotor blade with a solid foam material
using a liquid foam mixture that may be provided in the core area
through one or more openings of the rotor blade, in accordance with
certain embodiments. In at least one embodiment, the flowchart 1300
may begin at 1302 by providing a plurality of openings for the
hollow core area of the rotor blade. In some embodiments, the
openings may be outgas openings. In some embodiments, the openings
may be pour openings. In still some embodiments, the openings may
be injection openings in which a port may be configured for each
injection opening. In still some embodiments, the openings may be
injection openings in which no port may be configured for each
opening. In still some embodiments, at least one of the openings
may be an opening at the inboard end of the rotor blade.
The flowchart may proceed to 1304 by providing a liquid foam
mixture in the hollow core area of the rotor blade through at least
one opening of the plurality of openings in which the liquid foam
mixture expands and becomes a solid foam material that fills the
hollow portion of the rotor blade. It is to be understood that
different variations may be provided for the flowchart 1300 in
accordance with various embodiments described herein (e.g.,
heating/cooling the liquid foam mixture, adjusting the flow rate of
the liquid foam mixture, tilting the rotor blade, etc.).
The flowchart may proceed to 1306 by curing the solid foam
material. The flowchart may proceed to 1308 by sealing the
plurality of openings provided for the rotor blade. In at least one
embodiment, the flowchart may be completed following the curing at
1308. In some embodiments, however, the flowchart may restart
and/or certain blocks may be repeated.
The flowcharts and diagrams in the FIGURES illustrate the
architecture, functionality, and operation of possible
implementations of various embodiments of the present disclosure.
It should also be noted that, in some alternative implementations,
the function(s) associated with a particular block may occur out of
the order specified in the FIGURES. For example, two blocks shown
in succession may, in fact, be executed substantially concurrently,
or the blocks may sometimes be executed in the reverse order or
alternative orders, depending upon the functionality involved.
Although several embodiments have been illustrated and described in
detail, numerous other changes, substitutions, variations,
alterations, and/or modifications are possible without departing
from the spirit and scope of the present disclosure, as defined by
the appended claims. The particular embodiments described herein
are illustrative only, and may be modified and practiced in
different but equivalent manners, as would be apparent to those of
ordinary skill in the art having the benefit of the teachings
herein. Those of ordinary skill in the art would appreciate that
the present disclosure may be readily used as a basis for designing
or modifying other embodiments for carrying out the same purposes
and/or achieving the same advantages of the embodiments introduced
herein. For example, certain embodiments may be implemented using
more, less, and/or other components than those described herein.
Moreover, in certain embodiments, some components may be
implemented separately, consolidated into one or more integrated
components, and/or omitted. Similarly, methods associated with
certain embodiments may be implemented using more, less, and/or
other steps than those described herein, and their steps may be
performed in any suitable order.
Numerous other changes, substitutions, variations, alterations, and
modifications may be ascertained to one of ordinary skill in the
art and it is intended that the present disclosure encompass all
such changes, substitutions, variations, alterations, and
modifications as falling within the scope of the appended
claims.
One or more advantages mentioned herein do not in any way suggest
that any one of the embodiments described herein necessarily
provides all the described advantages or that all the embodiments
of the present disclosure necessarily provide any one of the
described advantages. Note that in this Specification, references
to various features included in `one embodiment`, `example
embodiment`, `an embodiment`, `another embodiment`, `certain
embodiments`, `some embodiments`, `various embodiments`, `other
embodiments`, `alternative embodiment`, and the like are intended
to mean that any such features are included in one or more
embodiments of the present disclosure, but may or may not
necessarily be combined in the same embodiments.
As used herein, unless expressly stated to the contrary, use of the
phrase `at least one of`, `one or more of` and `and/or` are open
ended expressions that are both conjunctive and disjunctive in
operation for any combination of named elements, conditions, or
activities. For example, each of the expressions `at least one of
X, Y and Z`, `at least one of X, Y or Z`, `one or more of X, Y and
Z`, `one or more of X, Y or Z` and `A, B and/or C` can mean any of
the following: 1) X, but not Y and not Z; 2) Y, but not X and not
Z; 3) Z, but not X and not Y; 4) X and Y, but not Z; 5) X and Z,
but not Y; 6) Y and Z, but not X; or 7) X, Y, and Z. Additionally,
unless expressly stated to the contrary, the terms `first`,
`second`, `third`, etc., are intended to distinguish the particular
nouns (e.g., element, condition, module, activity, operation, etc.)
they modify. Unless expressly stated to the contrary, the use of
these terms is not intended to indicate any type of order, rank,
importance, temporal sequence, or hierarchy of the modified noun.
For example, `first X` and `second X` are intended to designate two
X elements that are not necessarily limited by any order, rank,
importance, temporal sequence, or hierarchy of the two elements. As
referred to herein, `at least one of`, `one or more of`, and the
like can be represented using the `(s)` nomenclature (e.g., one or
more element(s)).
In order to assist the United States Patent and Trademark Office
(USPTO) and, additionally, any readers of any patent issued on this
application in interpreting the claims appended hereto, Applicant
wishes to note that the Applicant: (a) does not intend any of the
appended claims to invoke paragraph (f) of 35 U.S.C. Section 112 as
it exists on the date of the filing hereof unless the words "means
for" or "step for" are specifically used in the particular claims;
and (b) does not intend, by any statement in the specification, to
limit this disclosure in any way that is not otherwise reflected in
the appended claims.
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